Effect of Methyl Palmitate on the Formation of Epidural Fibrosis in an Experimental Epidural Fibrosis Model.

AIM: To investigate the effects of local and systemic administration of methyl palmitate on the formation of epidural fibrosis. MATERIAL AND METHODS: Twenty-eight rats were randomly divided into four equal groups (control, Spongostan, local methyl palmitate and orally methyl palmitate) and laminectomy was performed between T11 and L1 in all rats. Local methyl palmitate (300 mg/kg) was applied with Spongostan; methyl palmitate (300 mg/kg) was given orally three times per week on different days for a total period of 4 weeks. Four weeks later, the vertebral column from T9 to L3, including the paraspinal muscles and epidural scar tissue, was removed en bloc and epidural fibrosis and arachnoidal involvement was graded and evaluated histopathologically. Kruskal-Wallis and Pearson Chi-Square test were used for statistical analysis. A statistically significant p-value was determined as p < 0.05. RESULTS: The grading of epidural fibrosis was lower at a statistically significant level in orally-administrated methyl palmitate groups compared to the control and spongostan groups (p < 0.05). CONCLUSION: The findings of this study show that oral methyl palmitate decreases the formation of epidural fibrosis and that this effect of methyl palmitate could be mediated by reducing the functions of inflammatory cells such as macrophages, neutrophils and fibroblasts, including anti-inflammatory and antioxidant effects.

Assessment of epidural versus intradiscal biocompatibility of PEEK implant debris: an in vivo rabbit model.

PURPOSE: To understand the relative histopathological effects of PEEK particulate debris when applied within the epidural versus the intervertebral disc space. We hypothesized that due to the avascular nature of the intervertebral disc acting as a barrier to immune cells, the intradiscal response would be less than the epidural response. METHODS: The inflammatory effects of clinically relevant doses (3 mg/5-kg rabbit) and sizes (1.15 µm diameter) of PEEK implant debris were assed when placed dry on epidural and intradiscal tissues in an in vivo rabbit model. The size of the particulate was based on wear particulate analysis of wear debris generated from simulator wear testing of PEEK spinal disc arthroplasty devices. Local and systemic gross histology was evaluated at the 3- and 6-month time points. Quantitative immunohistochemistry of local tissues was used to quantify the common inflammatory mediators TNF-α, IL-1ß, and IL-6. RESULTS: Both treatments did not alter the normal appearance of the dura mater and vascular structures; however, limited epidural fibrosis was observed. Epidural challenge of PEEK particles resulted in a significant (30 %) increase (p < 0.007) in TNF-α and IL-1ß at both 3 and 6 months compared to that of controls, and IL-6 at 6 months (p < 0.0001). Intradiscal challenge of PEEK particles resulted in a significant increase in IL-1ß, IL-6 and TNF-α at 6-months post-challenge (p ≤ 0.03). However, overall there were only moderate increases in the relative amount of these cytokines when compared with surgical controls (10-20 %). In contrast, epidural challenge resulted in a 50-100 % increase. CONCLUSIONS: The results of this study are similar to past investigations of PEEK, whose results have not been shown to elicit an aggressive immune response. The degree to which these results will translate to the clinical environment remains to be established, but the pattern of subtle elevations in inflammatory cytokines indicated both a mild persistence of responses to PEEK debris, and that intradiscal implant debris will likely result in less inflammation than epidural implant debris.

Quantifying subtle but persistent peri-spine inflammation in vivo to submicron cobalt-chromium alloy particles.

PURPOSE: We evaluated the consequences of cobalt-chromium alloy (CoCr) wear debris challenge in the peri-spine region to determine the inflammation and toxicity associated with submicron particulates of CoCr-alloy and nickel on the peri-spine. METHODS: The lumbar epidural spaces of (n = 50) New Zealand white rabbits were challenged with: 2.5 mg CoCr, 5.0 mg CoCr, 10.0 mg CoCr, a positive control (20.0 mg of nickel) and a negative control (ISOVUE-M-300). The CoCr-alloy and Ni particles had a mean diameter of 0.2 and 0.6 µm, respectively. Five rabbits per dose group were studied at 12 and 24 weeks. Local and distant tissues were analyzed histologically and quantitatively analyzed immunohistochemically (TNF-α and IL-6). RESULTS: Histologically, wear particles were observed in all animals. There was no evidence of toxicity or local irritation noted during macroscopic observations in any CoCr-dosed animals. However, Ni-treated control animals experienced bilateral hind leg paralysis and were euthanized at Day 2. Histopathology of the Ni particle-treated group revealed severe neuropathy. Quantitative immunohistochemistry demonstrated a CoCr-alloy dose-dependent increase in cytokines (IL-6, TNF-α, p < 0.05) at 12 and 24 weeks. CONCLUSIONS: Subtle peri-spine inflammation associated with CoCr-alloy implant particles was dose dependent and persistent. Neuropathy can be induced by highly reactive Ni particles. This suggests peri-spine challenge with CoCr-alloy implant debris (e.g., TDA) is consistent with past reports using titanium alloy particles, i.e., mild persistent inflammation.

Spinal epidural Rosai-Dorfman disease preceding by relapsing uveitis: a case report with literature review.

STUDY DESIGN: Case report. SETTING: Tertiary referral center hospital in Taiwan. OBJECTIVES: To report a case of spinal Rosai-Dorfman disease (RDD) presenting with paraparesis and also preceding by relapsing uveitis for 6 months. A thoracic laminectomy was performed to remove the solid mass. The pathological diagnosis reveals infiltrating histiocytes, emperipolesis and positivity for S-100. There is no recurrence 1 year later with MR imaging. CONCLUSIONS: The relapsing idiopathic uveitis may be a prodrome for this unusual disease, because RDD is associated closely to defective immunogical response. Early and accurate diagnosis of CNS RDD may reverse the neurologic deficits by early decompression.

[Acute immune epiduritis in a child]. / Epidurite aiguë d'origine immunologique chez un enfant.

Acute epiduritis is an uncommon disease especially in children. We report an unusual case of acute epiduritis in a child, revealed by characteristic clinical signs and Magnetic Resonance Imaging (MRI). Given the absence of identified infectious or tumoral cause, and the ineffectiveness of antimicrobial treatment, a therapeutic test with polyvalent immunoglobulins was implemented. Rapid clinical improvement led to the retrospective diagnosis of probable immunological acute epiduritis.